Forecaster summary - Issued 2021-05-12T00:29:38

The high energy electron flux (greater than 2MeV) is expected to begin at mainly background levels, being suppressed in the presence of significant geomagnetic enhancements. Following the initial onset of the CME and high speed stream, which will excite and distort the radiation belts, the establishment of the high speed stream on day 1 or day 2 should lead to an input of electrons. This may then result in a rapidly increasing flux level from either late on day 2 (13 May), or more likely on day 3 (14 May). A sustained period of electron flux above the high (13epfu) threshold is then likely on day 4 (15 May).

Electron fluence is expected to remain at background levels through days 1 and 2, then increasing sharply through days 3 and 4, as the electron belts relax from their distorted states, resulting in a likely rise above the Active (1e8 integrated pfu) threshold.